From a random sample of 7 students in an introductory finance class that uses? group-learning techniques, the mean examination score was found to be 78.68 and the sample standard deviation was 2.5 For an independent random sample of 8 students in another introductory finance class that does not use? group-learning techniques, the sample mean and standard deviation of exam scores were 71.21 and 8.7 respectively. Estimate with 90?% confidence the difference between the two population mean? scores; do not assume equal population variances.

The 90?% confidence interval is from a lower limit of to an upper limit of